The US investment bank announced in July that Barroso, who was for 10 years the EU commission chief, was to become non-executive chairman and adviser on Brexit.

The move prompted an outcry on potential conflict of interest. It also caused a political backlash because Goldman Sachs was seen as a villain in the eurozone crisis because it helped Greece to hide the real level of its debt.

Last Friday (9 September), Barroso's successor Jean-Claude Juncker decided to have the case examined by en ethics committee. The commission, said Juncker in a letter to the EU Ombudsman, will send Barroso "a letter asking him to provide clarifications on his new responsibilities and the terms of reference of his contracts".

Juncker added that the former commission chief would also be treated as an ordinary lobbyist when he visits his former HQ.

In protocol terms, he would not get VIP access, but would have to get a visitor’s badge and undergo a security check.

“I have never sought a privileged position, but I would not expect to be discriminated against," Barroso said in the leaked letter.

Referring to the probe launched by Juncker, he said he "would like to understand how this decision has been taken, by whom and on what grounds."

"Not only are these actions discriminatory but they appear to be inconsistent with decisions taken in respect of other former members of the commission,” he added.

Barroso might have been thinking of the recent case of Neelie Kroes, one of his former commissioners, who joined the US car-sharing company Uber this year.

Kroes was commissioner for digital policies, a portfolio in which she dealt with the rise of Uber and other emerging internet companies.